Sea-Tac Airport in the western US state of Washington was put on lockdown after a security breach on Friday night.
Airport officials confirmed that Port of Seattle police responded to a breach alarm.
All entrances were closed and all trams were stopped after a man entered an area the wrong way.
The man was taken into custody for questioning, and the breach was cleared, and the lockdown was lifted after about 45 minutes.
But the lockdown caused a back-up at security check-points.